Adequate phosphate control in patients on hemodialysis (HD) is associated with decreases in intact fibroblast growth factor 23 (iFGF23), according to investigators.

Cristian Rodelo-Haad, MD, Reina Sofia University Hospital in Cordoba, Spain, and colleagues evaluated the effect of sustained control of serum phosphate on intact and c-terminal FGF23 (cFGF23) in 21 stable HD patients who were not receiving calcimimetics or active vitamin D. Patients received non-calcium phosphate binders to maintain serum phosphate levels below 4.5 mg/dL for 40 weeks. In an additional analysis, the investigators correlated values of iFGF and cFGF23 in 150 HD patients with parameters of mineral metabolism and inflammation.

During the 40-week period, 12 patients achieved the target serum phosphate levels. In these patients, iFGF23 concentrations decreased to less than half, whereas cFGF23 did not decrease significantly, the investigators reported in PLOS One. Among the 9 patients with serum phosphate above 4.5 mg/dL, iFGF23 and cFGF23 levels increased 2- and 4-fold, respectively, compared with baseline. Dr Rodelo-Haad and colleagues also observed that changes in serum phosphate correlated with changes in high-sensitivity C-reactive protein (hs-CRP), a marker of inflammation.

In the group of 150 HD patients, patients in the highest tertile of serum phosphate showed increased levels of hs-CRP, iFGF23, cFGF23, and intact parathyroid hormone.

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On multiple regression analysis, iFGF23 levels correlated directly with serum phosphate and calcium, and cFGF23 correlated with serum phosphate and hs-CRP, but not calcium, the according to the investigators.

“Our data support the concept that serum phosphate, FGF23 levels, and inflammation are closely interrelated,” the authors concluded. “These results may have clinical relevance because each of these parameters is associated with increased mortality.”

The authors noted that high FGF23 levels are strongly associated with cardiovascular disease and are an independent predictor of mortality. “Thus, control of FGF23 is likely a major issue in clinical practice.”